This invention relates to a magnetic head using a shunt biasing magnetoresistive element having a shunt film for application of a transverse biasing magnetic field. More particularly, the present invention is concerned with a magnetoresistive magnetic head which is particularly suitable for readout of a high-density magnetic recording.
As disclosed in, e.g., U.S. Pat. No. 3,940,797 and U.S. patent application Ser. No. 694,764, Ti, Ta, Mo, Au, Nb, etc. have been used for the shunt film of conventional shunt biasing magnetoresistive heads.
The shunt biasing magnetoresistive head having a shunt film made of Ti among the above-mentioned prior art has a drawback that a magnetoresistive film formed on a substrate and Ti react with each other at a temperature of 175.degree. C. or higher, causing the deterioration of the characteristics of the permalloy film. The production of a shunt biasing magnetoresistive head requires various processes. Such processes include a conductor film forming process, an insulating film forming process and a shielding film forming process, all of which are preferably conducted at a temperature of 175.degree. C. or higher. However, the processes requiring a treatment at a temperature of 175.degree. C. or higher could not be used because of the necessity of suppressing the deterioration of characteristics of the head. On the other hand, although the temperature at whcih a known shunt film made of tantalum begins to react with the permalloy it is unsuitable as a shunt film because of its poor corrosion resistance and extremely high electrical resistivity, i.e., 90 to 200 .mu..OMEGA.cm. It is preferable that the electrical resistivity of a shunt film be in the range of about 55 to 95 .mu..OMEGA.cm when the magnetoresistive film is made of a permalloy. The above-mentioned permalloy is a well-known Ni-Fe alloy containing 7 to 27 wt % of iron and commonly used as a magnetoresistive film. A conventionally known molybdenum film also does not react with a permalloy film until the temperature reaches 400.degree. C. or higher but is extremely poor in corrosion resistance. A gold film has the same problem as the above-mentioned titanium film and reacts with a permalloy film at a temperature as low as 150.degree. C. Further, a niobium film is unsuitable as a shunt film because it is not only poor in corrosion resistance as in the above-mentioned tantalum film, but also exhibits an extremely high electrical resistivity, i.e., 90 to 200 .mu..OMEGA.cm.
As is a apparent from the foregoing, the conventionally known shunt films were not satisfactory.
U.S. Pat. No. 3,864,751 is also cited to show the state of the art.